Influence of Jordanian Bentonite as Partial Replacement of Cement and Fine Aggregate on the Workability, Mechanical Properties and Impermeability of Concrete

Abstract

In recent decades, concrete prepared with bentonite clay has evolved as an accepted substitute of natural aggregate concrete due to the increasing focus on the development of sustainability and the environmental issues. In this research, the evaluation of possible and suitable use of Jordanian bentonite as a partial replacement of Ordinary Portland Cement (OPC) or fine aggregate in the production of concrete mixtures has been investigated. Bentonite has been used as 0, 5%, 10% and 15% by weight replacement of OPC or fine aggregate passing sieve No. 50 to conduct and compare the fresh properties, the mechanical strength and the permeability of concrete mixtures. Elemental compositions and crystalline phases of bentonite clay have been tested by using X-Ray Fluorescence (XRF) and X-Ray Diffraction (XRD), respectively. The test results have revealed that the compressive and flexural strengths have decreased as bentonite level has increased beyond 5% with substitutions of fine aggregate, whereas the compressive strength has decreased at every increased dosage of bentonite replacing partially the OPC. The strength activity indices have been higher than the ASTM C618 specified limit of 75%, except for the concrete mixture containing 15% bentonite replacing OPC. The incorporation of bentonite improves the permeation resistance of concrete and the enhancement is more pronounced at higher bentonite increments, especially when replacing the fine aggregate partially with bentonite.